1. Field of the Invention
A liquid collection device for use with various surgical procedures to control and monitor the rate of liquid flow from one or more body cavities.
2. Description of Prior Art
Various devices have been developed to collect and monitor blood loss from mediastinal and pleural drainage after cardiac and other thoracic surgery. Accurate monitoring of these blood losses is essential to determine the necessity for blood replacement. To insure an accurate measure, it is important that blood not accumulate in the patient long enough to clot and thereby distort actual blood loss.
Generally systems currently in use permit blood clotting in the mediastinal and pleural areas. This is particularly dangerous in patients with "whole blood" bleeding.
Blood clotting normally results from the failure to properly drain due to the geometry of the drainage tube between the catheter or catheters and the collection device. The drainage tube is usually a soft latex tube having a relatively large bore. The large bore is mistakenly thought to promote easier flow for the drainage components. The soft latex enables stripping or milking to facilitate drainage. Unfortunately this stripping causes negative pressures which may cause further bleeding.
These chest drainage collection systems usually include several dependent loops in the drainage tube. If the entire drainage system is devoid of air spaces, the vacuum created in the collection chamber should be transmitted to the pleural and/or mediastinal spaces ensuring continuous drainage. This reduces dwell time so that residence of blood in the pleural and mediastinal spaces is insufficient to permit blood clotting. In addition, a relatively large bore drainage tube creates a relatively large volume increasing dwell time and the possibility of clotting within the tubing.
Unfortunately, the relatively large bore of the drainage tubing creates a siphon break due to the inability to hold a column of liquid against gravity. In order to keep the downhill column filled with liquid, the internal diameter should be reduced. Proper sizing of the drainage tubing ensures that "uphill legs" do not cancel the negativity created by the vacuum. The pleural and/or mediastinal spaces, therefore, have the negative value imposed by the vertical height difference between the catheter tip and the point where the drainage tube enters the collection chamber except while there is actual flow in the collection tubing.
Typically such drainage systems include at least two chambers comprising blood reservoir disposed in series, where the first when full overflows into the second. Usually the first chamber has a smaller cross-section so that volumes can be read more accurately. If this is intended to serve and purpose, this purpose is defeated once the first chamber is full and further readings have to be made in the larger less accurate second chamber.
U.S. Pat. No. 3,363,626 and U.S. Pat. No. 3,363,627 describe in detail the anatomical and physiological environs in which such devices are employed as well as the earliest designs of "threebottle" drainage systems.
Specifically, U.S. Pat. Nos. 3,363,626 and 3,363,627 each discloses an underwater drainage apparatus comprising a unitary device having a collection chamber, underwater seal chamber and pressure regulating manometer chamber including an underwater seal saver to prevent the loss of the underwater seal during conditions of high negativity in a patient's pleural and/or mediastinal cavities.
U.S. Pat. No. 3,559,647 relates to an underwater drainage apparatus including a trap chamber, underwater seal chamber and pressure regulating manometer chamber. A baffle arrangement is provided to prevent loss of liquid from the underwater seal chamber and/or the pressure regulator chamber. A fluid flow meter is provided for measuring air flow through the underwater seal chamber and/or through the pressure regulator chamber.
U.S. Pat. No. 3,683,913 discloses an underwater drainage apparatus for evacuating fluids from body cavities comprising a integrally formed collection chamber, underwater seal chamber and pressure regulating manometer chamber. Air flow meters are disposed in the underwater seal chamber and the pressure regulating chamber to measure gas flow. A valve is provided between the underwater seal and the collection chamber preventing high negative pressures from being developed in the pleural cavity.
U.S. Pat. No. Re. 29,877 of U.S. Pat. No. 3,853,128 shows a drainage apparatus for evacuating fluids from cavities including a collection chamber for collecting fluids from a body cavity, a water seal chamber and a pressure regulator chamber. A valve mechanism is provided in the water seal chamber to permit the outflow of gases from the apparatus in the event of a sudden increase in pressure in the device resulting from respiratory movements or leakage of air.
U.S. Pat. No. 4,443,220 relates to a blood collection and transfer apparatus for autotransfusion in preoperative, operative and postoperative procedures.
Other examples of the prior art are found in U.S. Pat. No. 3,782,497 and U.S. Pat. No. 4,258,824.
Unfortunately such devices commonly permit blood clotting in the mediastinal or pleural spaces due to irregular drainage. In addition, the monitoring of continuous flow rates are not accurate.